The car below is a 1982 300CD (turbo). Federal car, as far as I can tell.

Transmission has been flaring, so I ordered a mityvac. Note that I have already disconnected the EGR, blocking the vacuum lines going to it where they originate.

As I understand, the off white thing sitting on top of the IP (with two lines out, one with a green inline thing) is the VCV - Vacuum Control Valve. This Ts into a 5-way connector, with lines going several directions, to the EGR, to supply, to the transmission.

I disconnected the line from the supply (furthest from the firewall) and attached the mityvac. It pumped up to only about 14"Hg, and slowly leaked down.

From reading other posts, I took that this was a leak at the modulator (green thing?) so I reconnected the supply line, and disconnected the line from the green inline device and plugged the mityvac into the device. Turning the car on, I expected some vacuum, but none (zero) was produced. Pumping up the mityvac, it went as high as 14"Hg and would hold there, with no leak.

I'm pretty sure the vacuum pump is working, because the door/trunk locks have been working perfectly ever since I got the car. Is this an indication that the VCV/Modulator (I'm not sure what the distinction is) is producing NO vacuum at all?

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1992 300D 2.5T 249k - Parked with a bad transmission
1981 300SD 142k - Daily driver